You will need to create the database user/password from the helm to connect to the database. Please follow the below steps for the same after logging in to helm:
1) Click on 'Domains' -> your domain name
2) Click on 'Database Manager'
3) Click on 'Add New' -> Enter database name -> 'Save'
4) On the successive screen, click on 'Add New' under the 'Database Users' section.
5) Enter database username/password and save. You can now use the username/password created in step 5 to connect using SQL server management studio or through visual studio or the SQL Server web admin.